I normally fill my 160k mile Peugeot HDI on normal diesel but when Costco started doing fuel I was filling it up there whenever I was passing/popping in and at 600 miles to a tank I manage to do so quite a bit and it definitely runs a little bit better. It was 99p/litre and they don’t sell standard diesel so it was actually cheaper than normal diesel from anywhere else but I am not sure what additives it has for cleaning etc.

I recently put BP Ultimate in the freelander before towing quite a heavy load and it definitely pulled better but at 124p/litre it’s eye wateringly expensive. Costco is at about 104p at the moment so almost 10p cheaper than normal diesel.

If I was buying the premium diesel all the time at a normal garage then I wouldnt bother but it makes sense when buying it from Costco and did help when towing a heavy load on a standard ECU map.